Palladium-catalyzed Enantioselective Decarboxylation of Vinyl Cyclic Carbamates: Generation of Amide-Based Aza-1,3-dipoles and Application to Asymmetric 1,3-Dipolar Cycloaddition

The catalytic asymmetric dipolar cycloaddition reaction is efficient for the construction of various chiral valuable carbo- and heterocycles. Thus, the design and exploration of new dipoles and the subsequent control of their reactivity for various stereoselective cycloadditions are significant aspects of modern organic synthesis. Herein, we have developed a series of vinyl cyclic carbamates containing an oxazolidine-2,4-dione fragment and used them as reactive precursors for in situ generation of amide-based aza-π-allylpalladium 1,3-dipoles, which could be applied to asymmetric decarboxylative 1,3-dipolar cycloaddition with different types of dipolarophiles containing C=C, C=N, and C=O double bonds. This strategy provides an opportunity for the synthesis of previously unusual structures, such as highly functionalized optically pure pyrrolidin-2-ones, imidazolidin-4-ones, and oxazolidin-4-ones. This protocol also has significant features including wide substrate scope, mild reaction conditions, simple operation, and good to excellent results (70 examples, up to 99% yield, >20:1 dr and 99% ee). This unique method significantly expands the reaction range of the amide-based aza-π-allylpalladium 1,3-dipoles compared to the precedents.